I recented stuck my tank badges on but purposely stuck them onto bare metal for better adhesion, did not get a problem. Rather than heat can you apply additional glue and then strap the badges in place with bungees while it dries?

sorry to hear you're having problems. I attached mine by using silicon sealant instead of the sticky strip and held them in place while the goo set using tape (gaffer/masking - not sure, 'twas 7 years ago).
A heat gun might help but I'm not offering guarantees! (A heat gun is one of my secret workshop magic tools. Much better than an oven or blow torch for heating cases when replacing bearings: heat at the flick of a switch.)

Out of interest, the transfer people who do the shows & advertise in the classic mags have stickers for Sport/Strada tank badges and I'm considering that option when I have my tank resprayed. I would like to get them offered as an alternative product offered by the club.